Preheat your oven to 375 degrees F (190 degrees C). If you have a good nonstick quarter sheet pan, spray it lightly with avocado oil. If not, line the pan with parchment paper and spray the parchment.
Add the egg whites, cornstarch, oregano, garlic powder, and onion powder to a large clean mixing bowl. Your bowl and beaters need to be completely free of grease and moisture or the whites will not whip properly.
Using a hand mixer or a stand mixer fitted with the whisk attachment, whip on medium until foamy, then increase to medium high and whip until stiff peaks form. The mixture should be glossy and smooth, and the peaks should stand straight up on the beater without drooping.
If using sourdough discard, drizzle the room temperature discard slowly over the whipped egg whites. Fold it in with a silicone spatula using slow deliberate strokes, going down through the center and sweeping up and over the sides of the bowl. Stop as soon as it is fully incorporated. Do not overfold or the foam will deflate.
Transfer the mixture to the prepared quarter sheet pan. Spread it evenly all the way into the corners, keeping the thickness consistent across the entire pan. Thin spots become tear lines when you roll.
Bake for about 10-12 minutes, until the surface is completely matte and dry with no shiny spots and the wrap is cooked all the way through. The edges should just begin to pull away from the pan.
Let the wrap rest in the pan for 5 minutes, then flip it out onto a wire cooling rack.
Cool completely before filling.
Fill and use as needed. Roll it as a wrap, slice it into pinwheels, or load it with whatever you have on hand, turkey and cheese, Caesar salad, buffalo chicken, or breakfast eggs and sausage.